Roger Federer hailed Queen Elizabeth II for her "elegance" and "grace" as the world of sport stopped to pay tribute to the British monarch following her death aged 96.
Sporting events in Britain scheduled for Friday, including Test cricket and European golf's PGA Championship, were canceled as a mark of respect.
British horse racing chiefs also pressed the pause button as tributes poured in for the queen across the sporting world.
In New York, there was a moment of silence at the US Open just before the women's semi-finals got underway.
"I am deeply saddened by the passing of Her Royal Majesty," tweeted Federer, who met the queen when she visited Wimbledon in 2010.
"Her elegance, grace and loyalty to her duty will live on in history," added the eight-time Wimbledon champion, who was not playing at the US Open.
Fellow tennis legend Rafael Nadal tweeted his "most respectful, sincere and deepest condolences".
